Liquid fuel catapult



2 Sheets-Sheet 2 c. M. HUDSON LIQUID FUEL CATAPUL'I' IEF.

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ATTORNEYS 2,986,072 LIQUID FUEL CATAPULT Colin M. Hudson, Arlington,Va., assignor to the United States of America as represented by theSecretary of the Army Filed Nov. 19, 1952, Ser. No. 321,534

1 Claim. 01. 89-7) (Granted under Title as, on. Code (1952), sec. 266)The invention described in the specification and claim may bemanufactured and used by or for the Government for governmental purposeswithout the payment to me of any royalty thereon.

This invention relates to guns and in particular to a novel system forpropelling projectiles from gun barrels or tubes.

In a gun, when the charge is fired, the gas pressure immediately beginsto rise in the powder chamber. The projectile at first remainsstationary because of the friction fit with the bore but beyond acertain pressure the friction bond is broken an the projectile begins tomove forward in the bore. This movement tends to relieve the pressure byincreasing the volume within which the gases may expand. But the burningof the charge is not instantaneous and the powder continues to burn andevolve gases as the projectile moves. As long as the projectile is inthe bore it is acted upon by a fairly high pressure which reaches amaximum at some point between its original position and the muzzleandfunctions as an accelerating force. The point in the bore at which theprojectile is driven by maximum pressure is determined by a number offactors and in many of the prior art guns this point is about a foot inadvance of the powder chamber. As will later more fully be explained myinvention will yield a substantial advance in the art of propellants byproviding a controlled rate of pressure generation leading to higherprojectile velocities at lower peak pressure.

It is a broad object of my invention to improve on the weapons now inuse.

It is a further and more particular object of my invention to provide asystem for propelling projectiles in which highly reactive liquidchemicals are used in place of the conventional solid propellants.

It is a still further object of my invention to provide a reactivechemical Weapon which is completely safe to op crate, and is reliable inuse.

Other objects of the invention will be evident from the followingdescription and the appended drawings in which:

Figure 1 is a fragmentary longitudinal section view of my novel weapon.

Figure 2 is a section view taken along lines 2-2 of Figure 1 and lookingin the direction of the arrows.

Figure 3 is a section view taken along lines 3-3 of Figure 1 and lookingin the direction of the arrows.

Figure 4 is a fragmentary longitudinal section view of another speciesof my novel weapon.

Figure 5 is a section view taken on lines 5-5 of Figure 4 and looking inthe direction of the arrows.

Figure 6 is a fragmentary longitudinal section view of still anotherspecies of my invention.

Figure 7 is a section view taken on lines 7--7 of Figure 6 and lookingin the direction of the arrows.

Described briefly my invention consists of a system whereby selfigniting chemicals may be intimately intermixed so that theirspontaneous reaction produces the pressures for projectile ejection andflight.

In the specification and in the claim appended thereto the word"hypergolic is intended to be used as defined in the Defense DepartmentsGlossary of Guided Missile Terms, Capable of igniting spontaneously uponcontact.

Refening now more particularly to Figure 1, wherein a cartridge is usedfor the pressure source reference character 1 indicates generally abreech block having at the forward end thereof a barrel or tube 2threadedly received in a cavity and aligned with a combustion chamber 3.Passages 4 and 5 lead from chamber 3 on opposed sides thereof and holdcylinders 6 therein. The cylinders are each provided with an orifice 9in the end wall proximate the combustion chamber which orifice isnormally covered with a frangible plug, and have a piston 7 for apurpose that will presently appear. The bores 4 and 5 are closed attheir distal ends by plugs 12 which may be removed to insert thecylinders in a loading operation. Leading rearwardly from the outerportion of bores 4 and 5 are two arms 13, 14 of a forked cavityterminating in a cartridge chamber having nested therein a cartridge 15;A plug 16 slidable in breech block 1 has a lifting eye 17 thereon andcarries a spring biased firing pin 18 so ar-f ranged that when the plugis properly seated in the breech block the firing pin is aligned withthe primer in the cartridge.

The several injector cylinders 6 are adapted to receive the hypergolicfluids. In general a reactive fuel 19 is contained in one cylinder andan oxidizer 20 is contained in the other. Specific examples of suchcombinations that have been successfully used are hydrazine (N H withhydrogen peroxide (H 0 and hydrazine with nitric acid. It will beunderstood however that the above examples are illustrative only and myinvention contem plates the use of any and all substances and compoundsthat react spontaneously and violently upon contact.

It can be readily seen that upon firing of the cartridge 15 by movingfiring pin 18 forward, the gases of combustion create a high pressure inpassages. 13 and 14 and transmit same to the outer faces of pistons 7.The pistons will urge inwardly upon the confined hypergolic fuel 19 andoxidizer 20 fracturing the frangible covering over the orifices 9 andthe several liquids will empty there through and intermingle withincombustion chamber 3 with a resultant spontaneous chemical reaction andthe production of a high pressure to force projectile 21 out of thebarrel.

Attention is now directed to Figures 4 and 5 wherein a variant of mynovel weapon is revealed. Reference character 22 indicates a breechblock having at the forward end thereof a barrel 23 threadedlyreceivedin a cavity and aligned with passageway 24 which is selectivelyclosed by sliding plate 29. A traverse passage in tersects passage 24 toform a combustion chamber 30. On opposed sides of the chamber areslidable injector pistons 31 and 32 having ports 33 and 34 in the closedends thereof and constructed to slidably receive bosses 35 and 36 formedon the ends of plugs 37 and 38 respectively. Pipe line 39 having a oneway check valve 40 serves to connect with a pressurized sourcecontaining one of the hypergolic fluids and to a bore in plug 37; andpipe line 41 having a one way check valve 42 serves to connect apressurized source of the other reactant to a bore in plug 38.

The weapon is illustrated in condition for firingand a cycle thereofwill now be described. A valve (not shown) is triggered whichsimultaneously admits metered amounts of the hypergolic fluids at a highpressure into pipes 39 and 41 respectively. The reactants will quicklyfill the volumes between boss 35 and cylinder 31 and between boss 36 andcylinder 32 and a portion of each will be ejected through ports 33 and34 into combustion chamber 30 where they will meet and intermingle tocreate a pressure. This pressure acting upon the exposed face ofcylinders 31 and 32 will force them toward bosses 35 and 36 respectivelythus emptying the filled volumes into. the combustion chamber with greatforce and the resulting explosion willsend projectile 28 upon itstrajectory. .It.

should be noted that the area of the cylinder face exposed to combustionchamber pressure is greater than the area of the cylinder-face exposedto the fluid pressure. Thus a regenerative piston effect is obtained andthe pressure of the fluid can be greater than the initial pressure inthe chamber but the resultant force will still move thepistonbackforcing the reactant therein into the chamber.

. After .the projectile has leftthe muzzle of the barrel the chamberpressure drops and the cylinders are returned to their forward positionby expansion of the trapped air compressed behind the open ends of thecylinders during rearward motion thereof and a projectile feedingmechanism (not shown) lifts sealing block 29 up and forces a newprojectile into the barrel ready for the next shot.

It can be readily seen that the amount of propellant is readilycontrolled by limiting the amounts fed to the pistons or limiting themotion thereof whereby the point of maximum pressure acting on theprojectile may be adjusted. Also the rate of propellant injection may becontrolled by proper selection of piston face areas.

Another species of my invention is disclosed in Figures 6 and 7.Reference character45 indicates generally a breech block secured tobarrel 4.6 which is shaped to form a chamber to receive a novelarrangement of the hypergolic fluids. A metallic casing holding aprimer54 at thev rear thereof holds the hypergolic liquids incombustible elongated containers arranged longitudinally within thecasing with each liquid sandwiched between two dissimilar onessubstantially as shown in Figure 7 wherein, for example, referencecharacters 47, 49 and 51 indicate a reactive fuel and 48, 50 and 52indicate an oxidizer. A projectile '53 is frictionally held in thebarrel and a firing pin 55 is aligned with the primer 54 in the usualmanner. I

' When the firing pin explodes the primer the flame moves down thelongitudinal axis of the chamber and destroys the containers. Thehypergolic liquids thereupon mix and the resulting reaction ejects theprojectile from the barrel.

Among the advantages offhgabove described invention are: (1) higherpropellant s by reason of the lowered propellant gas molec';

,l (roo which are obtainable with such reactant combinations as suchmixtures, (2) controlled rate of pressure generationby control overpropellant injection rates, leading to higher velocities at lower peakpressures, and (3) comparable velocities at lower ratios of propellantto projectile weight by reason of the above, so that less propellant andchamber volume is required resulting in a shorter gun.

An extensive series of firings has been conducted on a gun built inaccordance with the principles set out in this invention. A projectilevelocity of 6200 ft./sec.' at a propellant'to projectile mass ratio of3.6 was obtained: For a propellant to projectile mass ratio of 1.5 themaxi mum velocities exceeded nitrocellulose values by'as much as 20% atcomparable or lower chamber pressures. Velocities as high as 8700ft./sec. have been attained at substantially lower peak pressures thanpublished figures for nitrocellulose powder.

In a general manner I have in the above description disclosed what Ideem to be practical and efiicient embodiments of the present invention.It should be well understood that I do not wish to be limited thereto asthere might be changes made in the arrangement, disposition and form ofthe parts without departing from the principles of the present inventionas comprehended 'within the scope of the accompanying claim.

I claim:' 4 i A firearm comprising a breech casing, a barrel afiixed tosaid breech casing, a combustion chamber formed in said casing andcommunicating with said barrel, at least two opposed bores in saidcasing one end of which corn-. municates with said combustion chamber, acounterbore at the other end of said bores, hollow injection cylindersfixedly received within said counterbores, said cylinders containing apredetermined volume of hypergolic reactants and having at one endthereof a normally sealed orifice opening into said bores, a piston atthe other end of said cylinders, a pressure generating cartridgereceived within said casing, a series of passages in said casingcommunicating between said pistons and said cartridge, whereby saidpistons are actuated to break said seal and inject said reactants intosaid combustion chamber in response to firing said cartridge.

References Cited in the file of this patent UNITED STATES PATENTS1,970,017 Peake Aug. 14, 1934 2,573,471 Malina et 'al. Oct. 30, 1951FOREIGN PATENTS 164,697 Great Britain June 9, 1921 405,645 Great BritainJan. 29, 1934 1,003,687 France Nov. 21, 1951 OTHER REFERENCES Journal ofthe American Rocket Society, No. 72, December 1947, Liquid PropellantRocket .Power Plants by Dr. M. I. Zucrow, pages 31-932. (Copy in Div.46.)

